The present invention generally relates to air ventilating equipment, and more particularly relates to apparatus and methods for ventilating the interior of a truck cab which may include a sleeper compartment.
During both short rest stops and overnight sleeping stops in warm weather it is quite common for truck drivers to leave their truck engines idling to power the truck's air conditioning system so that the interior of the cab is maintained at a desirably cooled temperature. This continuous engine idling, of course, wastes fuel and tends to shorten the operating life of the engine. Over a given year it is not uncommon for the engine to be kept at idle for this limited purpose for 200 to 300 hours per month.
Various alternatives have heretofore been proposed to eliminate, or at least substantially reduce, the need for such sustained periods of engine idling. One approach has been to provide a temperature control system which, during rest or sleep stops, cycles the truck engine (and thus the cab air conditioning system) on and off as needed to maintain a predetermined cooled temperature within the cab. While this method uses less fuel, it is still fuel inefficient and increase the wear and tear on the engine and starter due to the many additional engine start-ups required.
Another approach has been to provide a small fuel-powered auxiliary engine which, with the truck engine off, powers only the cab air conditioning system during rest and sleep stops. While this method eliminates the excessive main engine idling problem., it still can use considerable fuel, and additionally increases the overall expense and complexity of the truck's mechanical and electrical systems.
Yet another scheme for cooling the truck cab during rest and sleep stops has been to simply turn off the truck engine and rely on the vent structures typically installed in ventilation passages in the sleeper compartment exterior walls, or other exterior walls of the cab, to provide cooling outside air ventilation to the cab interior. Vent structures of this type are manually adjustable from the interior of the cab to selectively permit or preclude outside air flow into the cab via the ventilation passages, and may be pivotable blade louver structures, or dual sliding plate structures with alignable air flow openings therein.
These manually operable vent structures provide a simple and quite inexpensive alternative to the conventional use of an idling truck engine to power the cab air conditioning system. However, this alternate approach to cab cooling has proven to be less than entirely satisfactory for several reasons. For example, the amount of outside ventilation air entering the typical vent structure when the truck is stopped tends to be quite small. Accordingly, only a minimal cooling effect is achieved which may not be sufficient in hot weather. Additionally, when a conventional vent structure of this type is opened for cooling ventilation purposes it forms an opening through which all types of insects may enter the cab. Placing a screen or filter over the vent structure can eliminate this problem, but also greatly reduces the amount of outside cooling air which can enter the cab.
It can be readily be seen that a need exists for improved apparatus and methods for cooling and ventilating a truck cab during rest and sleep stops which eliminate or at least substantially reduce the above-mentioned problems, limitations and disadvantages typically associated with conventional truck cab ventilation and cooling approaches. It is accordingly an object of the present invention to provide such improved apparatus and methods.